DESCRIPTION: The long-term goal of these studies is to determine how synthesis of proteins is regulated post-transcriptionally during spermatogenesis. The first specific aim is to purify and characterize the protein. Here the principal investigator proposes to take advantage of RNA affinity chromatography methods, where the protein will bind to its target RNA sequences immobilized on sepharose. Purified protein will be analyzed by microsequencing. The second aim will be to isolate cDNA for TB-RBP as well as construct antibody and to use these reagents to define the extent of the TB-RBP gene families and to determine the cellular and subcellular distribution of TB-RBP. The third aim is to determine the RNA recognition sites of the TB-RBP. This will be done by methods of site-directed mutagenesis of the target RNA sequences and the end goal is to better understand how TB-RBP binds to and inhibits mRNA translation. The fourth aim is to define the sites and mechanisms of phosphorylation and dephosphorylation of TB-RBP.